Hi, welcome to Perl, the One True Religion. There is more than one way to do it. You should use a database for this.

If you install DBD::SQLite, the Perl driver for sqlite, you get, as the doc says, "a Perl DBI driver for SQLite, that includes the entire thing in the distribution. So in order to get a fast transaction capable RDBMS working for your perl project you simply have to install this module, and nothing else."

In the example below, I simply create a database from the data, and then use the SQLite client on my computer to run a query. You could of course extend the Perl script to run the query after loading the data (and if so, you may not need to write a DB file at all, see :memory: as a database name) ... adding such queries to the script is left as an exercise for the reader.

$ cat 11106779.pl
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use strict;
use warnings;
use DBI;

my @AoH = ({
    targetL => 'foisonnement',
    origin  => 'AMG',
    count   => '1',
}, {
    targetL => 'foisonnement',
    origin  => 'IDBR',
    count   => '1',
}, {
    origin  => 'IWWF',
    targetL => 'gonfler',
    count   => '1',
}, {
    origin  => 'IWWF',
    targetL => 'due',
    count   => '1',
}, {
    origin  => 'IWWF',
    targetL => 'due',
    count   => '1',
});

my $dbh = DBI->connect('dbi:SQLite:dbname=11106779.db','','', { RaiseE
+rror => 1 });

$dbh->do('create table data(targetL varchar(32), origin varchar(16))')
+;

my $sql = 'insert into data (targetL, origin) values (?, ?)';
my $sth = $dbh->prepare($sql);
$sth->execute($_->{targetL}, $_->{origin}) for @AoH;

__END__
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$ perl 11106779.pl
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( ^ note no output; no errors )

$ sqlite3 11106779.db
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SQLite version 3.24.0 2018-06-04 14:10:15
Enter ".help" for usage hints.
sqlite> .headers on
sqlite> select origin, targetL, count(origin) count from data group by
+ origin, targetL order by count desc;
origin|targetL     |count
IWWF  |due         |2
AMG   |foisonnement|1
IDBR  |foisonnement|1
IWWF  |gonfler     |1
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Hope this helps!